The invention concerns a heat-stable oil-in-water emulsion and a process for its preparation. Great Britain Complete Patent Specification No. 1 525 929 concerns a water-in-oil emulsion with a phospholipoprotein containing material (for example egg yolk) modified by phospholipase A (PLA). This emulsion is stable, i.e., when exposed for 30 min. to 100.degree. C. Although this emulsion is effectively heat-stable, the great disadvantage is that the egg yolk is enzymatically modified, and secondly, the suppression of any residual activity of PLA by proteases is not possible since the proteolytic enzymes would modify the egg yolk proteins and PLA alone can only be inactivated at a very high temperature (160.degree. C.).